Shunkashuutou Daikousha: Hyakka Hyakuyou

With the power bestowed upon them by the Gods, the Agents of the Four Seasons bring the seasons to the world. It is their duty to traverse mountains and valleys to bring the blessings to every corner of the world. Each Agent has a special guard for if anything happens to them the seasons stop to cycle. Sakura Himedaka is the guard of Hinagiku Kayo, Agent of Spring. Ayame Hazakura guards Ruri Hazakura, Agent of Summer. Rindo Azami guards Nadeshiko Iwaiduki, Agent of Autumn. Itecho Kangetsu is the guard of Rosei Kantsubaki, Agent of Winter. They have just gone through battles with those who aim to destroy the system. This is a vivid story of four Agents and four guards who wish to protect the world but are also individuals who fall in love.
(Source: BookWalker)